This invention relates to plunge type routers and, more particularly, to an arrangement for locking the router at a desired depth of cut.
Plunge type routers are similar to conventional routers in that they include a drive motor secured within a motor housing, the motor having a shaft which extends outwardly beyond the lower end of the motor housing, with the shaft adapted to have a cutting tool secured thereto. The router also includes a base plate which is displaceable substantially vertically relative to the motor housing. In conventional non-plunge type routers, the motor is locked in position relative to the base plate such that the cutting tool projects axially beyond the lower workpiece engaging surface of the base plate to the desired depth of cut at all times. However, plunge type routers provide biasing means which operate to retract the cutting tool above the workpiece engaging surface of the base plate during periods of non-use. In order to enable a plunge type router to be "plunged" to the desired cutting depth, such routers are also commonly provided with adjustable depth stop systems and may also include arrangements for locking the motor housing relative the base plate at preselected positions, such as the cutting depth. It is therefore a primary object of this invention to provide a depth of cut locking arrangement for use with a plunge type router.
Plunge type routers typically include a pair of handles by means of which the operator may hold and guide the router during use. These handles are also used when the operator "plunges" the router to its desired depth of cut. Once at the desired depth of cut, the motor housing and base plate are preferably locked relative to each other so that the operator may concentrate on guiding the router without at the same time maintaining sufficient downward pressure on the motor housing to maintain the desired depth of cut. However, if the operator must release his grip on the router handle in order to effect the locking function, this may result in an inadvertent change of the depth of cut. It is therefore another object of the present invention to provide such a depth of cut locking mechanism wherein the operator does not have to release the handle.
It is a further object of this invention to provide a release mechanism for the locking arrangement.
Since the parts of a router are subject to wear, it is yet another object of the present invention to include in the locking arrangement some means to provide adjustable compensation for such wear.